A process for the manufacture of a 1,2-epoxide is described in the published European patent application EP 2149569. It describes the catalytic oxidation of a terminal olefin using a water soluble manganese complex as the oxidation catalyst.
The process described is carried out in a multiphasic, e.g. biphasic system, i.e. a system comprising an organic phase, which may be a liquid or a gaseous phase, and an aqueous phase. The actual reaction takes place in the aqueous phase, while the resulting epoxide product separates from the aqueous phase into the organic phase due to low solubility of, or extraction or stripping by the organic phase. For this reason, the 1,2-epoxide is produced at high turnover numbers (TON), with high selectivity towards the 1,2-epoxide with moreover improved ease of isolating the produced 1,2-epoxide.
Typically the catalyst system used to achieve the above advantages comprises a manganese atom or a number of manganese atoms coordinated with a ligand or ligands. Of particular interest are binuclear, manganese complexes. As an example of the above manufacture of 1,2-epoxide, reference is made to the European patent application publication EP 2149570, which describes the oxidation of allyl chloride to produce epichlorohydrin. EP 2149569 denotes further that the process may be carried out in a reactor, but does not elaborate on this. It turned out, however, that upon isolation of the 1,2-epoxide, an aqueous phase was left which comprised an active catalyst fraction. EP 2149569 does not describe any further use for this fraction, meaning that part of the catalyst is wasted, which is not efficient. Another example about a manufacturing method of propylene oxide is presented in the non-published European patent application 09075528.